The present invention relates generally to lawn and garden tractors or similar vehicles, and more specifically to an interlock circuit and detent switch for such a vehicle.
Vehicles such as some lawn and garden tractors with PTO driven attachments include an interlock circuit with several functions including the prevention of PTO operation when the vehicle is placed in reverse and stopping of the engine when the operator leaves the seat. Under certain conditions, operation of the PTO while the vehicle is in reverse is necessary. Various override systems have been proposed for this purpose. For example, one type of available override system on a mower allows PTO operation when the vehicle is backing up, but only after the PTO is automatically disconnected during the shift into reverse. Another type requires the operator to continuously push a switch during reverse operation. Further types are shown in U.S. Pat. Nos. 6,316,891 and 5,994,857 of common ownership with the present application.
Problems with some of the previously available systems is that the PTO switch can remain in the on position under certain conditions when relays have been deactivated by the interlock system and the engine stops or the PTO is disengaged. In the engine kill situation, the operator must first return the PTO switch to the off position to restart the engine, but often the operator initially fails to notice that the PTO switch is on and tries other options first. When PTO operation is interrupted, the operator must reactivate the PTO by moving the switch back to the on position. Although such systems have provided the necessary interlock and override functions, they are not as intuitive and user-friendly as systems wherein the position of the PTO switch actually corresponds to the operational state of the PTO.
It is therefore an object of the present invention to provide an improved interlock system for a vehicle such as a lawn and garden tractor. It is another object to provide such a system which overcomes most or all of the aforementioned problems.
It is a further object of the present invention to provide an improved interlock system for a vehicle such as a lawn and garden tractor with a PTO or similar attachment drive switch wherein the on and off positions of the switch correspond directly to the on and off conditions of the driven attachment, even if the attachment drive is disabled or the engine is stopped by action of an interlock system.
It is yet another object of the present invention to provide an improved interlock system for a vehicle such as a lawn and garden tractor with a bypass circuit allowing operation in reverse under certain conditions. It is a further object to provide such a circuit with an improved PTO or attachment drive switch wherein switch position corresponds directly to the PTO or attachment drive condition. It is another object to provide such a circuit having a switch that moves to the off position if the vehicle engine is shut down or if the interlock circuit is operated to disable drive to the attachment.
It is another object of the present invention to provide an improved switch for controlling drive to an attachment on a lawn and garden tractor or similar vehicle. It is still another object to provide such a switch which is particularly useful for interlock circuits with a bypass system to allow operation of an attachment in reverse under certain conditions.
It is yet another object to provide such an improved switch for controlling drive to an attachment on a lawn and garden tractor or similar vehicle, the switch including an actuation device to move the switch handle to an off position in response to an interlock circuit on the vehicle interrupting drive to the attachment so that switch position corresponds to the actual attachment on or off condition. It is a further object to provide such a switch which returns to the off position when the engine is killed.
A PTO switch for the attachment drive of a lawn and garden tractor includes a solenoid activated detent to retain the normally off switch in an on position. The switch includes an interlock override position for permitting a function such as mow in reverse. An interlock circuit interrupts drive to the attachment under certain conditions. Once drive is interrupted for any reason, the solenoid deactivates and the switch is moved to the off position so that PTO switch position corresponds to attachment drive condition, even when the drive is interrupted by means other than movement of the switch. Since the switch is returned to the off position, the problems associated with the operator failing to notice that the PTO switch is on are reduced or eliminated. Machine disruption and operator frustration are minimized, and the time necessary for the operator to get the machine back up and running after an engine kill or PTO interruption is reduced.